This is a note to let you know that I've just added the patch titled
device-dax: fix cdev leak
to my char-misc git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git
in the char-misc-testing branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will be merged to the char-misc-next branch sometime soon,
after it passes testing, and the merge window is open.
If you have any questions about this process, please let me know.
>From 03e61923cac2e8f6b24eeeaf8e8bd17b6ebe5b88 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Date: Mon, 6 Mar 2017 00:04:18 -0700
Subject: device-dax: fix cdev leak
If device_add() fails, cleanup the cdev. Otherwise, we leak a kobj_map()
with a stale device number.
As Jason points out, there is a small possibility that userspace has
opened and mapped the device in the time between cdev_add() and the
device_add() failure. We need a new kill_dax_dev() helper to invalidate
any established mappings.
Fixes: ba09c01d2fa8 ("dax: convert to the cdev api")
Cc: <stable@xxxxxxxxxxxxxxx>
Reported-by: Jason Gunthorpe <jgunthorpe@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Reviewed-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/dax/dax.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/drivers/dax/dax.c b/drivers/dax/dax.c
index 8d9829ff2a78..a5ed59a5a968 100644
--- a/drivers/dax/dax.c
+++ b/drivers/dax/dax.c
@@ -675,13 +675,10 @@ static void dax_dev_release(struct device *dev)
kfree(dax_dev);
}
-static void unregister_dax_dev(void *dev)
+static void kill_dax_dev(struct dax_dev *dax_dev)
{
- struct dax_dev *dax_dev = to_dax_dev(dev);
struct cdev *cdev = &dax_dev->cdev;
- dev_dbg(dev, "%s\n", __func__);
-
/*
* Note, rcu is not protecting the liveness of dax_dev, rcu is
* ensuring that any fault handlers that might have seen
@@ -693,6 +690,15 @@ static void unregister_dax_dev(void *dev)
synchronize_rcu();
unmap_mapping_range(dax_dev->inode->i_mapping, 0, 0, 1);
cdev_del(cdev);
+}
+
+static void unregister_dax_dev(void *dev)
+{
+ struct dax_dev *dax_dev = to_dax_dev(dev);
+
+ dev_dbg(dev, "%s\n", __func__);
+
+ kill_dax_dev(dax_dev);
device_unregister(dev);
}
@@ -769,6 +775,7 @@ struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
dev_set_name(dev, "dax%d.%d", dax_region->id, dax_dev->id);
rc = device_add(dev);
if (rc) {
+ kill_dax_dev(dax_dev);
put_device(dev);
return ERR_PTR(rc);
}
--
2.12.0